Apparatus for tobacco treatment



Sept. 23, 1941. H. L. SMITH JR., ETAL 2,256,954

APPARATUS FOR TOBACCO TREATMENT Original Filed Dec. 21, 1937 3Sheets-Sheet l ATTO RNEYS,

P 1941- H. 1.. SMITH JR.. ET AL 2,256,954

APPARATUS FOR TOBACCO TREATMENT Original Filed Dec. 21, E337 3Sheets-Sheet 2 1 .7- 45 W37 --45 47 ll i g 47 BY gawfigwww ATTORNEYS.

S Sheets-Sheet 3 H. L. SMITH JR. ET AL APPARATUS FOR TOBACCO TREATMENTOriginal Filed Dec. 21, 1937 Sept. 23, 1941.

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ATTORNEYS.

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Patented Sept. 23, 1941 2,256,954 APPARATUS FQR TOBACCO TREATMENT HoraceL.

Smith, Jr., and Lucian N. Jones, Richmond, Va., assignors to TheGuardite Corporation, a corporation of Illinois Original applicationDecember 21, 1937, Serial No. 180,987. Divided and this application July22, 1940, Serial No. 346,815

4 Claims.

" improved apparatus for altering the moisture content and ofexterminating undesired organisms in tobacco.

We have heretofore devised a tobacco treatment process by means of whichthe moisture content of tobacco may be quickly and easily increased orotherwise adjusted, and by means of which, the expense, delay and lossesinvolved in previously known moistening procedures are avoided. In thatprocess, which is disclosed in detail in our Patent No. 2,086,446, andin our copending application, Serial No. 54,443, filed December 14,1935, the tobacco is successively subjected to a high vacuum, suppliedwith steam with a reduction in degree of vacuum, and again subjected toa relatively high vacuum with the result that the moisture content ofthe tobacco is quickly increased without undesirable discoloration orother deterioration of the tobacco. The successive steaming andre-evacuating steps may obviously be repeated one or more times ifdesired. As disclosed in our patent above referred to, this process isalso efiective in exterminating organisms which infest tobacco.

It is the general object of the present invention to provide improvedapparatus which may be used in carrying out these and related processes.We have found that moisture can be supplied to tobacco more effectivelyand in larger quantities by modifying our aforesaid process ashereinafter explained. The improved apparatus is particularly useful inthe treatment of tobacco which is tightly packed in hogsheads, bales orthe like, and may also be used in the treatment of loose tobacco. Likethe original process, the improved process and apparatus are effectivein exterminating pests which infest tobacco in all forms of their lifecycle.

A feature of our present invention is supplying both water and steam tothe tobacco, the water preferably taking the form of a fine mist orspray entrained in the steam and injected therewith into the evacuatedspace containing the tobacco. When steam under pressure is introduced toa previously evacuated area, the reduction in pressure, unaccompanied bythe performance of work, liberates heat, which results in superheatingof the steam. The water introduced with the steam is vaporized, thesuperheat of the steam supplying the necessary latent heat ofvaporization. The steam is thus ie-superheated with the result thatunnecessary heating of the tobacco by the steam is avoided. We prefer tointroduce with the steam an amount of water considerably in excess tothat'necessary to de-superheat the steam at the reduced pressure,whereby excess water, preferably in the form of a fine spray, suspensionor mist, is entrained with the steam and carried into contact with thetobacco structure thereby. This is preferably accomplished by breakingup or atomizing a stream of water within or substantially within thepreviously evacuated treatment chamber at or adjacent the point wherethe steam is introduced thereto. Other ways of introducing steam andwater may be employed, but we believe that the method generallydescribedis preferable because the water de-superheats the steam as thesuperheat is developed, and the steam assists in breaking up the excesswater into a fine mist or suspension of particles and immediatelyentrains this mist and carries it into intimate contact withthe tobacco.The introduction of water may accompany each steaming operation whetherone or more steaming steps or stages are employed.

The improved apparatus of our invention comprises a novel means forsimultaneously injecting steam and water into a previously evacuatedtreatment chamber in such a manner that the steam is de-superheated andexcess water is formed into a fine suspension or mist and introducedwith the steam and carried thereby into intimate contact with thetobacco or other material in the chamber. In a preferred embodiment,this means includes a nozzle structure having therein means fordirecting a stream of water under pressure into impinging contact with asurface whereby the water isbroken into a mist in the presence of thesteam. The structure preferably directs the steam adjacent the point ofimpingement of the water stream, whereby the stream assists in atomizingthe water and entrains the water mist (or the proportion thereof whichhas not immediately vaporized in desuperheating the steam), and sweepsit out of the nozzle opening into the treatment chamber. In one form ofthe invention, the nozzle structure is so constructed and mounted withrelation to a tobacco treatment chamber that impingement of the streamof steam and entrained water against the chamber walls is minimized.This prevents considerable loss of entrained water in the introducedfluid prior to its contact with the tobacco or other material undertreatment.

In describing the invention in detail, reference willi 1101c made'to theaccompanying drawings, in w c Figure 1 is a diagrammatic and simplifiedillustration of apparatus capable of carrying out our improved process IFigure 2 is a sectional view of improved steam and water injectingapparatus embodying certain features of our invention; and

Figure 3 is a graph illustrating the various steps to which tobacco maybe subjected in a typical treatment cycle embodying certain features ofour invention.

Various forms of apparatus. may be employed in carrying out'our improvedprocess. The illustrative apparatus diagram, shown in Figure 1, includesa pair of tobacco chambers .4 and 4' of substelftially identicalconstruction. The two chambers are employed to permit the loading of oneat the same time that tobacco is being treated in the other. The processcould obviously be carried out in a single chamber. The chambers shownare cylindrical and are provided with removable doors or closures 5 and5' at each end thereof to permit the introduction and removal of thetobacco to be treated. Since our process involves subjecting the tobaccoto a high vacuum, the treatment chambers 4 and 4' are air tight and thedoors 5 and 5' are provided with suitable gaskets or other sealing meanswhich prevent the admission of air while a process is being carried out.Each chamber 4 and 4' is preferably large enough to accommodate severalhogsheads of tobacco and suitable means may be provided for introducingthe hogsheads and removing them from the chambers. Suitable means areprovided for selectively evacuating or drawing fluid from the chambers 4and 4'. Although various means may be used for this purpose, wegenerally prefer to employ multi-stage steam jet evacuators which wehave found to give excellent results. The illustrated apparatus includesa three-stage steam jet evacuating system but a greater or smallernumber of stages 'may be used where warranted by the conditionsencountered.

As shown, the chambers 4 and 4' are respectively connected through thesuction line valves 6 and 6' with a common T fitting I opening into theinlet of a first stage steam J'et ejector or booster 8. The first steamjet booster 3 discharges through a. pipe 9 into an intercondenser ID.The intercondenser 10 may take any suitable form, and as shown,comprises a direct contact condenser of known construction. Theintercondenser I is supplied with water through a pipe ll under controlof the valve l2. Water and condensate are withdrawn from theintercondenser IO through a pump l3 constructed to prevent the ingressof air to the condenser. The fluid outlet of the intercondenser I0 isconnected to the inlet of a second stage steam jet ejector l4 whichdischarges into a second intercondenser IS. The intercondenser I may besimilar in construction to the first stage intercondenser l0, but ispreferably of smaller capacity. Water is supplied to the intercondenserl5 from the pipe I I under control of a. valve I 6, and condensate andwater are withdrawn by a sealing pump l'l. Two third-stage steam jetejectors l8 and I8 are connected in parallel to withdrawn fluid from thesecond intercondenser IS. The ejectors l8 and It may discharge steam andevacuated fluid to the atmosphere directly through an exhaust pipe ill,or a final condenser may be employed to condense the exhaust steam, ifdesired. A trapped drain 2|! is preferably provided to carry off theliquid which condenses in the exhaust pipe is, and the-liquid from thisdrain may be either wasted or recirculated through a cooling system thepipes 35' and with the discharge from the condenser pumps l3 and I1.

The steam jet ejectors 3, l4, l3 and I8 are of known construction, eachemploying a jet of steam to propel and compress gaseous fluid byentrainment in a restricted throat. High pressure steam for operatingthe ejectors is supplied from any suitable source through a pipe 2| inwhich a separator 22 of known construction may be connected. The firststage steam booster 8 receives steam through a branch pipe 22' under thecontrol of an automatic valve 23 and a hand valve 23'. The second andthird stage ejectors receive steam from the pipe 24. The automatic valve25 and manual valve 25 govern the admission of steam to the second stageejector l4 and the automatic valve 26 and manual valve 28 control theadmission of steam to the third stage ejector l8 and 13 in parallel.

Suitable means are provided for admitting steam to the treatment chambes4 and 4'. 'In the disclosed embodiment, steam is introduced at aplurality of points spaced longitudinally by means of the manifold pipes21 and 21' and the branch pipes 28 and 28' which terminate in openingsin the chamber walls. The manifold pipes 21 and 21' are connected to thesteam supply pipe 2| through automatic control valves 29 and' 28, and

manual valves 30 and 30' may also be used at this point, as shown.Restricted by-pass pipes 3| and 3! are preferably connected respectivelyaround the automatic steam control valves 29 and 29' to admit steam at arestricted rate to the chambers 4 and 4 at certain times, as hereinafterexplained. Water may be introduced with the restricted steam supply ifdesired. Automatic control valves 32 and 32' are provided in the by-passpipes 3| and 3| respectively.

In accordance with one embodiment of our invention, water isintroducedto the treatment chambers with steam, and for this purpose, watermanifold pipes 33 and 33', each having branch pipes 34 and34', areprovided for the respective chambers 4 and 4'. The branch pipes 34 and34' are connected to s aced openings in the walls of the chambers 4 and4' respectively, and preferably enter these chambers at the same pointsas the branch steam pipes 28 and 28'. The admission of water iscontrolled by the automatic valves 46 and 46 in the manifold pipes 33and 33' respectively and manually operable valves 53 and 50' may also beprovided for this purpose.

Suitable means are provided for venting the chambers 4 and 4' to theatmosphere. Asshown, 35', controlled respectively by the valves 36 andThe pipes 35 and 35' are shown as connected to the chambers 4 and 4'through the fittings which connect the suction line valves 6 and 6' tothe chambers. The vent pipes could obviously be connected to thechambers at any other conven-v ient point.

The supply of steam and water to the steam jet ejectors and theintroduction of these fluids to the treatment chambers, as well as theventing and evacuation of the chambers, may be controlled manually byseparate valves, manually from a central point or by suitable automaticcontrol apparatus. The particular form of control valve actuationemployed forms no part of the present invention but in many instancesboth manually operable and automatic valves have been disclosed toindicat the different types of actuation which may be resorted to. Thesuc-.

tion line controlled valves 6 and 6' are preferably 36' are used forthis purpose.

)1 large capacity and are usually operated by diaphragm or electricmeans, of known construction. the remaining automatic valves may besimilarly operated.

In accordance with one feature of our invention, water is introduced tothe treatment chambers with the steam during the steaming steps orstages including the soaking stage if desired, and is converted into afine mist or suspension and entrained with the steam as the two fluidsenter the chamber. We have devised an improved apparatus for performingthis function and it is illustrated in Figure 2. In this figure, thewall of a treatment chamber is illustrated at 4, a steam supply pipe at23' and a water supply pipe at 34. These parts may comprise thecorrespondingly designated parts of the apparatus shown in Fig. 1.

The water and steam injecting device or nozzle shown comprises a hollowinlet bushing 31 connected to the inner end of a collar 38 which iswelded or otherwise sealed in an opening through the wall of the chamber4. The collar 38 is connected through a nipple 39 and a T fitting 49 tothe steam supply pipe 28 and the water supply pipe 34 passes axiallythrough the parts 38 and 39 and is sealed in an opening of the T fitting49 by a suitable packed gland 41. The end of the water pipe is fixed toa water nozzle fitting 42 in communication with a central water passage43 of small bore which terminates in a nozzle opening 44. The fitting 42is threadedly connected within the inlet bushing 31 and is provided witha plurality of steamopenings 45 disposed about the central water passage43. A deflecting disc D is fixed in spaced relation to the inner end ofthe fitting 31 by suitable means such as the bolts 41. The disc Dextends across let of the fitting 31 and preferably comprises a planecircular central portion 48 surrounded by a frustoconical or tapered rimportion 49. The disc D cooperates with the inner end of the fitting 31to form a finid outlet nozzle which directs the discharged fluidoutwardly substantially par allel to the wall of the treatment chamber.

Water is supplied through the pipe 34 at a relatively high pressure andaccordingly issues from the water nozzle 44 in a fine stream at highvelocity and impinges upon the plane central portion 48 of the disc Dwhere it is broken up into a fine mist or suspension. The steam from thepipe 28 flows through the openings 45 toward the disc D, and aids inbreaking up the water into fine particles. The contact between the waterand steam at the reduced pressure within the treatment chamber resultsin the vaporization of some of the water with a resultantde-superheating of the steam, and the excess water over that thusvaporized is entrained by the steam and carried out through the nozzleopening formed by the disc D and the fitting 31. Since the nozzleopening directs the injected fiuid in an initial path substantiallyparallel to the treatment chamber wall, the loss of water from thisfiuid by impinging contact against the chamber wall at high velocity isminimized.

After curing, tobacco is customarily tightly packed in hogsheads, balesor the like and is aged in warehouses for periods which may run toseveral years. The tobacco loses moisture during aging and as a resultbecomes so dry and brittle that is cannot be unpacked, much less handledor stemmed, without excessive loss from shattering, tearing or powderingof the leaf structure. The process of the present invention may beemployed to increase the moisture conthe out-' tent at various stagesduring the preparation or shipment of tobacco, and also to exterminateorganisms in tobacco with or without altering its moisture content. Theprocess has proven particularly effective in the'so-called ordering" ofaged and relatively dry packed tobacco, that is, increasing the moisturecontent of such tobacco to a point where it can be unpacked and stemmedwithout substantial breakage of the leaf structure. Our process will behere described by reference to a typical example thereof as employed inordering tobacco.

The tobacco, which is usually packed in hogsheads or bales, is placedwithin one of the treatment chambers, for example, the chamber 4. Theheads may be removed from the hogsheads before treatment if desired, butthis operation is not essential since tobacco hogsheads are not fluidtight. The doors 5 of the treatment chamber 4 are closed and the tobaccois subjected to a series of operations which have been graphicallyillustrated in Figure 3, where the ordinates represent absolute pressurein the treatment chamber in inches of mercury, and the abscissarepresent time in minutes.

The tobacco in the treatment chamber 4 is first subjected to arelatively high vacuum, as indicated by the portion abcd of the curve inFigure 3. The degree of vacuum should be such as to remove substantiallyall of the air initially contained in the treatment chamber and theinterstices of the structure of the tobacco therein. We have found thatthe degree of vacuum required for this purpose varies somewhat with the.temperature of the tobacco. Thus with tobacco having an initial minimumtemperature of about 70f F. or higher, a vacuum from 29.5 to 29.6 inchesof mercury (.5 to .4 inch Hg absolute pressure) is sufficient, whereaswith lower initial minimum temperatures of the tobacco mass,

v vacuums as high as 29.85 to 29.95 or even higher may be required. Inthe example illustrated in Figure 3, the, initial minimum temperature ofthe tobacco mass is assumed to be in the neighborhood of 70 F., and theinitial vacuum is drawn to about 29.65 inches of mercury (.35 inch of Hgabsolute pressure).

The steam jet evacuating equipment described may be operated in variousways to produce the desired initially high vacuum and the followingsequence of operations has been found effective and economical. Thesuction line valve 6 is opened and the valve 6' controlling the chamber4 is closed, the valves 36, 23,

and 46 being closed. The steam supply valve 26 for the third stageejectors l8 and I8 is opened and these ejectors, acting in parallel,reduce the absolute pressure by withdrawing fiuid from the treatmentchamber 4 as indicated by the portion ab of the curve abce in Figure 3.At about the point b, it is preferred to start the second stage ejectorl4 and this is done by opening the steam valve 25. At the same time,cooling water is admitted to the second intercondenser I5 by opening thewater valve l6, and in this manner, the steam issuing from the'ejectorI4 is condensed before it reaches the third stage ejectors l8 and 18'.When the absolute pressure of the chamber has been further reduced to avalue such as that indicated by the point 0 on the curve, the firststage booster 8 and first intercondenser III are operated by opening thesteam valve 23 and the water valve 12. With all of the ejectors inoperation, the absolute pressure on the tobacco is rapidly re- 3 to anintermediate duced to. the desired final value, as indicated by thepoint d in Figure 3. As shown in Figure 3, the entire evacuatingoperation can be completed in a relatively short interval, less thantwelve minutes in the illustrative example shown. At the conclusion'ofthe initial evacuating step, the suction line valve is closed and theejectors and intercondensers are shut down by closing the valves 23, i2,25, I6 and 26.

After the desired high, vacuum has been attained, steam is supplied tothe tobacco whereby the vacuum thereon is reduced. In accordance withone feature of our invention, water is supplied to the tobaccosimultaneously with the steam, the amount of water so supplied beinggreater than that .required to de-superheat the steam at the vacuumobtaining in the chamber. The simultaneous addition of water and steamis efi'ected by opening the steam valve 29 and the water valve 46, andthe pressure within the chamber increases as shown at de on Figure butpreferably sub-atmos- Dheric value. We believe that the excess waterintroduced is carried into intimate contact with the tobacco by thesteam which flows rapidly intothe previously evacuated tobaccostructure. In this manner, the moisture content of the tobacco isincreased, both by the condensation of steam and by the water introducedwith the steam During the steaming step, the absolute press re should beincreased to such a value that the steam, and entrained water wherewater is introduced therewith, will quickly penetrate the tobacco massand moisten it substantially uniformly throughout. The steam introducedheats the tobacco and raises its temperature, and the amount of steamintroduced, as determined by the absolute pressure sion of the steamingstep, should not be so high as to cause discoloration or other heatdeterioration of the tobacco tained. In accordance with our process, theabsolute pressure attained in the steaming step produces a tobaccotemperature high enough to cause discoloration of the tobacco after atime interval, but prior to the expiration of such interval, theabsolute pressure is reduced sufliciently to appreciably lower thetobacco temperature, whereby discoloration or other heat deteriorationis avoided. .This reduction of absolute pressure takes place in there-evacuating step or steps as hereinafter described. In the exampledisclosed in Figure 3, it is assumed that bright tobacco is undertreatment, and the absolute pressure at the end of the steaming step isabout ten inches of mercury (a vacuum of about 20 inches of mercury).When the process is applied to burley tobacco, which is more resistantto heat than bright tobacco, the absolute pressure at the end of thesteaming step may reach a value in the neighborhood of 12 inches ofmercury (a vacuum of 18 inches of mercury).

With various varieties of tobacco and times of treatment, the finalsteaming pressure may vary between about 8 and 18 inches of mercuryabsolute. The steaming step is terminated by closing the steam and watervalves 29 and IS.

The amount of water introduced during the steaming step is preferably inexcess of that required to de-superheat the steam supplied to thetobacco whereby an excess of water, in the form of a fine mist orsuspension, is carried into the tobacco structure by the steam; Theamount attained at the conclu-.

I lbs. per square inch assuming that 25 lbs. per

of water so introduced is not critical, and amounts from twice to fouror iive times the amount necessary to de-superheat the steam may beused. In a typical example of our process,

minute of dry saturated steam at an initial pressure of about 115 gaugeis introduced through each branch pipe 28, about .7 gal. of water perminute may be introduced with the steam through each branch pipe 34. Inthe example given, assuming an initial vacuum of about 29.5 inches ofmercury in the chamber, approximately .35 gal. per minute of water wouldbe suiiicient to saturate (de-superheat) the steam introduced at eachbranch pipe.

The water is preferably introduced to the tobacco chamber at the samepoint as the steam whereby the steam is de-superheated as the superheatdevelops and the water is broken up and entrained by the steamas itenters the chamber. The atomizing or breaking up of the water may bepromoted by the use of known type of atomizingor spray nozzles, or theimproved nozzle illustrated in Figure 2 and described above may beemployed for this purpose. One or more combined water-and steam inletsmay be provided, and good results are obtained by using one such inletfor each hogshead, bale or other mass of tobacco in the treatmentchamber 4. When our improved steam and water injecting nozzle is used,one such device may be provided at each inlet point and within the timeinterval during which the elevated temperature is mainlocated adjacenteach tobacco hogshead.

A so-called soaking step preferably follows the introduction of steamand water. During this portion of the process, the absolute pressure onthe tobacco is maintained constant or nearly constant for a limited timeinterval as indicated by the portion cf of the curve of Figure 3. Thepreviously introduced steam continues to condense after the introductionof steam has been discontinued, and accordingly, the pressure in thechamber 4 would, normally fall during the "soaking period. Accordingly,we prefer to introduce steam at a low rate substantially sufllcient tocontinuously replace the steam being condensed, whereby the absolute 1pressure on the tobacco is maintained substantially constant. This maybe accomplished by opening the steam valve 32 in the restricted bypasspipe 31, it being understood that the rate of steam flow through thispipe is reduced by the pipe size, a'restricted orifice or otherwise toproduce the desired continuous replacement of the steam being condensedin the chamber. The introduction of steam at a restricted rate duringthe soaking stage may, if necessary or desirable, be accompanied by theintroduction of water in the form and amounts explained above. Thesoaking step is terminated by closing the valve 22.

At the conclusion of the "soaking step, the tobacco is subjected toan-increased vacuum, the pressure thereon being reduced as indicated bythe portion fa of the curve in gure'" 3. The degree of evacuation towhich the tobacco is subjected in this step is preferably high enough tovaporize or evaporate some moisture from the tobacco whereby itstemperature is reduced, heat being absorbed in the form of latent heatof vaporization. This re-evacuating step may comprise the iinal step ofthe process, and the evacuation preferably continues to an absolutepressure at which sufllcient moisture has been evaporated or vaporizedto reduce the tobacco temperatures in the perature to a safe value. Theheat discoloration and other heat deterioration of tobacco is a functionof the temperature, the time for which the temperature is maintained andthe type of tobacco under treatment. If certain types of bright tobaccoare maintained at'temperatures above about 125 F. for an extended timeinterval, discoloration and often other forms of heat deterioration takeplace, and the value of the tobacco is thereby substantially reduced.However, these tobaccos may be maintained at temneighborhood of about180 F. about 10 or 15 minutes without discoloration or other detrimentalchange. In general, bright tobacco is more sensitive to heat than othervarieties, burley tobacco, for example, will withstand high temperaturesfor appreciably longer periods than will bright tobacco.

The re-evacuating step jg of our process is continued to a value ofvacuum at which the temperature of he tobacco by the evaporation orvaporization .of moisture to a value at which heat deterioration willnot take place. This temperature, and accordingly, the final value ofvacuum, varies as indicated above depending upon the type oftobacco-under treatment.- The treatment to which the tobacco issubjected after the conclusion of our process is also a factor in fixingthe final tobacco temperature. In most cases, the tobacco is unpackedfrom the hogsheads or bales and the leaves are separated immediatelyafter the ordering treatment. With this procedure, the tobacco is cooledby the atmosphere promptly after the treatment process is concluded andaccordingly the temperature to which the tobacco is reduced in there-evacuating step may be somewhat above the minimum temperature atwhich heat deterioration can take place after an extended interval. Ifthe tobacco is not to be unpacked at the conclusion of the process, there-evacuation is continued until the tobacco temperature is below thelowest temperature at which it can be adversely effected, by heat in anytime interval.

In the disclosed example, assuming bright tobacco is under treatment andis to be unpacked at the conclusion of the process, the re-evacuatingstep fa. is continued to a vacuum of about 27.25 inches of mercury (2.25inches of mercury absolute pressure). This final vacuum may vary fromabout 25 to about 29.8 inches of mercury (5 to .2 inches of mercuryabsolute pressure) and in the case of very dark heat resistant tobaccos,which are to be unpacked immediately after treatment, the final vacuummay be as low as 20 inches of mercury (10 inches of mercury absolutepressure).

The re-evacuating step jg may be performed by operating the third stageejectors l8, l8 and the first stage intercondenser i until the absolutepressure has been reduced to some intermediate point, such as the pointk. The second stage ejector l4 and the second intercondenser l5 may thenbe operated by opening the valves 25 and i6 and the absolute pressure isfurther reduced to the point g by the second and third stage ejectorsacting in series. If desirable or necessary, the first stage booster 8may also be operated in drawing the desired vacuum. The re-evacuationstep is concluded by closing the suction line valve 6 and cutting offthe supply of steam and water tothe ejectors and intercondensers.

At the conclusion of the treatment chamber for intervals of there-evacuating step jg, 4 is vented by opening has been reduced on thetobacco indicated by the the valve 36, and the pressure risestoatmospheric pressure as curve section gh. The tobacco is now removedfrom the treatmentchamber 4 and the processis V complete.

It is obvious that the above described steaming and re-evacuating stepsmay be repeated one or more times if desired. One such repetition hasbeen illustrated by the broken line curves starting at the point a inFigure. 3. Since a second steaming, "soaking and re-evacuating cycleconsumes only a short time interval, the tempera; ture to which thetobacco is cooled in the first re-evacuating step may be somewhat higherthan the temperature required at the conclusion of the treatment. Thus;as shown in Figure 3, the first re-evacuating step may continue untilthe absolute pressure is reduced to about 4 inches of mercury (a vacuumof 26 inches of mercury). In general, a practical working range ofabsolute pressures at the conclusion of an initial re-evacuating stepmay be from about 3 to about 5 inches of mercury absolute.

The first re-evacuating step in the case of recycling may beaccomplished by manipulating the apparatus as described above. It isusually necessary to operate the third stage ejectors l8 and I8 and thefirst intercondenser I0 only, although operation of the second stageejector l4 and second intercondenser l5 may be resorted to during a partof the re-evacuating step, if necessary or desirable.

The re-evacuating step just described is followed successively by arepetition of the steaming, soaking and re-evacuating steps. The secondsteaming step is indicated by the broken line g'h', the second soakingstep is indicated by the line hi and the second re-evacuating step isindicated by the broken curve section y'k'l. These steps may berespectively performed by manipulating the apparatus as described abovein connection with the steaming, soaking and re-evacuating stepsrepresented by the curve sections de, ef and IQ. The second steamingstep gh' is usually of shorter duration than the first steaming step de,the absolute pressure on the tobacco at g being somewhat higher thanthat at d, and the final steaming or soaking pressures beingsubstantially the same in each case. At the end of the finalre-evacuating step a'k'l, the treatment chamber is vented to theatmosphere, as indicated by the line lm, and the tobacco is removed fromthe chamber. The "soaking step is believed to aid in the uniformdistribution of moisture in the tobacco. By introducing water with thesteam, the amount of moisture added to the tobacco is increased withoutundesirably increasing the maximum temperature to which the tobacco isheated.

Our improved process exterminates tobacco pests, such as the cigaretbeetle, in all forms of its life cycle. This can be done simultaneouslywith the addition of moisture as described above, or without net changein the moisture content. In the latter case, the reevacuating step iscontinued until all of the added moisture has been evaporated orvaporized and removed.

It should be understood that the described examples ar merelyillustrative and that our invention is not limited to the values ofpressure and vacuum or the time intervals set forth above and indicatedin Figure 3. The various features of our invention may be separatelyemployed.

Although the process practiced in the apparatus of the present inventionhas been described may be applied to other steps in the treatment oftobacco or other materials where it may be found applicable. Forexample, we have found that our above described process is effective indestroying mold and mold spores which sometimes appear in aged tobacco.We have also found that our process is eflective in tempering andimproving the quality of cased tobacco, that is, tobacco to whichflavoring materials have been added. In either the destruction of moldor mold spores or the tempering of cased tobacco, our process may be soconducted as to increase the moisture content of the tobacco or withoutnet chang in the moisture content, and in the latter case, there-evacuation is continued until all or substantially all of the addedmoisture has been evaporated. This application is a division of ourapplication Ser. No. 180,987, flied Dec, 21, 1937 which has matured intoPatent 2,217,935, dated Oct. 15, 1940.

We claim:

1. Apparatus for injecting a mixture of water and steam into a treatmentchamber comprising a water nozzle, a plate aligned with but spaced fromsaid water nozzle and disposed across the path of water issuing fromsaid nozzle, and means adjacent said water nomle for directing steaminto contact with said plate in a path substantially parallel to andsurrounding the water issuing from said water nozzle.

2. Apparatus for injecting a mixture of water and steam into a treatmentchamber comprising tral portion thereof and a restricted nozzle having asubstantially straight bore, a plate extending across said nozzle andspaced therefrom in the path of fluid issuing from said nozzle, aplurality of fluid openings adjacent said nozzle and directed towardsaid plate and means for supplying water to said nozzle and supplyingsteam to said fluid openings. 3. Apparatus for injecting a mixture ofwater and steam into a treatment chamber comprising a. water nozzlehaving a restricted bore. a plate having a substantially plane surfacespaced from and disposed across and in alignment with the bore of saidwater nozzle and having tapered edges, and a plurality of steam nozzlesdisposed around said water nozzle and directed toward said plate.

4. Apparatus for injecting a mixture 'of water and steam into atreatment chamber comprising a substantially circular plate having aplane central portion and tapered marginal edges, means spaced from saidplate for directing a stream of water into impinging contact with saidplane cenmeans spaced from said plate for directing steam against saidplate ad- Jacent the point where the water impinges thereon.

HORACE L. SMITH, Jn. LUCIAN N. JONES.

